Ultrasound can replace CT and MRI for neurosurgical navigation

23 Nov 2010

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Aloka Holding Europe AG is working with internationally
renowned neurosurgeon, Dr Klaus Resch of the University of Greifswald
and Klinikum München in Germany to promote the potential for ultrasound
to be used in conjunction with, or as a replacement for, CT/MRI as a
neuro-navigational tool in certain operations.

As part of this initiative, Dr Resch has this month begun planning
to extend his training programme for neurosurgeons across all of
Latin America following a successful pilot with surgeons in Mexico
[1]. He will be announcing the full results of the Latin American
initiative at the Neuroendoscopy 2011 conference taking place in
Guadalajara (Mexico).

Dr Resch believes ultrasound has been greatly underused in
neurosurgery over the past 20 years. He said, "I strongly advise all
neurosurgeons to widen their imaging tools beyond just CT and MRIs.
Intra-operative ultrasound can solve many problems that cannot be
achieved with other imaging techniques."

“We are discovering new surgical uses of ultrasound daily and its
use in the developing world could have enormously positive
implications to patient safety — as the use of CT and MRI is low in
these countries due to its prohibitive costs”

Dr Resch bases his recommendation on a 1084-patient case study he
conducted on the uses of ultrasound in surgery, one third of which were
observed intra-operative and two thirds peri-operatively [2].

In this,
he was able to prove conclusively that ultrasound was an excellent neuro-navigational system, which provided the surgeon with both
real-time imaging and targeting capabilities in all of the
intra-operative cases he observed (376 cases). In addition, it was
also demonstrated that neurosurgical therapy outside the operating
room could be markedly assisted by ultrasound.

For a number of years, Dr Resch has been a pioneer in the use of
neurosurgical ultrasound and has discovered a broad variety of
applications and indications both intra- and peri-operatively. He
conducted his research using four bespoke Aloka probes in a variety
of settings — including the TCD probe (use: intensive care unit),
the small part sector probe (use: intra-operative), and the
burr-hole probe (use: intra-operative).

Examples of Aloka ultrasound probes used for
neurosurgery

The findings showed that ultrasound enabled the surgeon to be
more reactive during surgery, with real-time images showing exactly
how the lesion is being manipulated and how the brain reacts. In
plain terms, this means the surgeon can view what is happening as he
operates, without the need to stop the operation to obtain new
images (ie from CT or MRI), which can be very dangerous for the
patient.

In addition, ultrasound is also preferable to CT or MRI during
these cases as, with real-time images, there is no risk of error due
to the brain shifting. Furthermore, the surgeon can also quickly
locate vascular feeders and the source of any bleeding — a common
and life threatening problem during operations.

Example of ultrasound used in neurosurgery

A (top left), aqueduct. The sonoprobe (1) is entering the aqueduct
(white asterisk) at the posterior third ventricle formed by
hypothalamus (2) and posterior commissure (3).

B (top right), aqueduct and posterior fossa. The sonoprobe (1) is
inside the aqueduct of the mesencephalon (2). As the zoom is
very low, the posterior fossa is scanned with the cerebellum
(3), clivus, and petroclival border (4), as well as the
tentorial notch on the right side (5).

C (bottom left), fourth ventricle. The sonoprobe (1), as well as the
inferior vermis (2) bulging into the ventricle covered by
the variant of a circular plexus (3). The superior medullary
velum (4) limits the inferior view while a view into the
depth of the foramen of Magendi (9) is possible. The facial
colliculus (6) and medial eminence (5) are seen on both
sides, divided by the medial sulcus (asterisks). Laterally,
the vestibular area (7) is visible, as is the entry to the
foramen of Luschka (8).

Additionally, Dr Resch has shown in Mexico that ultrasound could
provide an invaluable surgical tool in the developing world, where
the cost of procuring an MRI or CT scanner is highly prohibitive in
comparison to an ultrasound unit.

“Due to the cost-effective nature, logistical ease of use, and
ergonomic character of ultrasound, it could have profound
implications in the developing world and, this November, I will
begin expanding my training programmes for neurosurgeons across all
of Latin America. However, high-end neurosurgical ultrasound depends
entirely on having selected the appropriate probes and Aloka
technology has been a big contributory factor in advancing its
clinical uses.”